A suraromu book punishes a bad file in a way a sample puzzle never shows. Your buyer judges puzzle forty-one, when the key's loop crosses a long gate twice, or crosses the gate marked 3 before the gate marked 2, or returns to the starting circle having passed nine gates on a page whose circle promises ten, and the solver who trusted the order concludes the fault is theirs. Suraromu, also called Slalom, looks scenic: a rectangular grid scattered with black cells, dotted lines running between black cells and out to the frame, and one cell holding an open circle with a number in it. The solver draws a single loop that sets off from that circle, threads the whole course, and comes home. It is a contract in five parts, each part exact. First, the loop rule: one single loop, drawn through the centres of cells horizontally and vertically, never crossing itself, never branching, and never passing through the same cell twice. Second, the gate rule: the continuous dotted lines between black cells, or from a black cell to the outer frame, are gates — a dotted run that spans several cells is still one gate — and the loop must pass every gate, perpendicularly through it, exactly once. Third, the start rule: the loop starts at the cell with the open numbered circle and returns to that same cell, and the number in the circle is the total number of gates on the course. Fourth, the order rule: a number in a black cell at the end of a gate says when the loop crosses that gate — a gate marked 1 is crossed first out of the start, a gate marked 4 is crossed fourth, in either direction around the loop — while a gate with no number may be crossed at any point. Fifth, tying it shut: exactly one solution, reachable by deduction alone, with no guessing. A puzzle that breaks any part is not slightly harder. It is false as stated. A good suraromu book is a verified set: every loop on every page re-walked from the start circle, gate by gate, in order, puzzle by puzzle.
One warning belongs at the front, because it is the mistake this genre makes most often, and it starts with the name. Suraromu is not gokigen. Both puzzles have been nicknamed "slalom" in print somewhere — gokigen naname, the diagonal puzzle, travels as Slant and sometimes as Slalom too — and the two games share nothing else: gokigen puts one diagonal in every cell so that corner numbers count the diagonals touching them and no diagonals close a loop, while suraromu writes no diagonals at all and its whole object is one loop, crossing gates in a stated order. A setter, a cover designer, or a marketplace listing that borrows gokigen language — diagonals, corner counts — for a suraromu book teaches the buyer a game the pages do not contain, and the returns and one-star reviews arrive addressed to the wrong puzzle. The second half of the same warning is what a gate is. A gate is the whole continuous dotted run, not each dotted segment: a run spanning three cells, crossed once, is one gate crossed once, and a key that counts it as three has miscounted the course and will disagree with the number in the starting circle. The one subtle case belongs on the rules page too: when a numbered black cell touches more than one gate, its number belongs only to the gate that carries that same number at both ends. Name the puzzle correctly on the cover — suraromu, or Slalom, saying so if you use the alternate name — state its own rules on its own rules page, and verify with the rule as printed: one loop, every gate once, the circle's number is the gate total, and the black-cell numbers are a crossing order, not decoration.
The book is the puzzle set, not the sample grid
Buyers do not buy a grid style. They buy the promise that every puzzle in the file obeys the rules printed at the front, at the difficulty the cover claims, in the order the book presents them. A free sample almost never breaks that promise, because a sample is the one puzzle the setter checked three times. The breakage lives at puzzle forty-one, in the middle of the book, where a generator exported the loop from one grid and the gate numbers from the next, or a hand-setter moved one black cell, split a gate in two, and never recounted the course. That is why the unit of quality in a puzzle book is the whole set, verified as a set: the same checks, run the same mechanical way, on every single puzzle, with the results kept. If you generated the puzzles, keep the generator's settings per puzzle, including the grid size. If you set them by hand, keep your solving notes. When a buyer writes in about one puzzle — and in this genre they write in with the page number and the gate they cannot reach in order — you want to answer about that puzzle, not go hunting through a file you can no longer reconstruct.
The rules page is part of the product, not decoration. State all five parts of the contract in plain language, with one small worked example showing a short loop leaving the start circle, crossing its first gate — the one marked 1 — and coming home past the last, with the gates ticked off in crossing order as the walk goes. That ordered walk is the one idea a new buyer must carry away, and it is the idea a short rules page most often drops in favour of a pretty picture of a finished loop with no order shown. Most one-star reviews in this genre are not "too hard" or "too easy". They are "the loop cannot be drawn" — and that mismatch is almost always a setter who held the real course in their head, or in the generator, and printed a set that was never re-walked from its own key.
The contract, part by part
The gate rule is the identity of the puzzle, so check it like one. Gates are defined by the black cells and the frame, which means moving a single black cell can merge two gates into one, split one gate into two, or change which gates a numbered cell belongs to — while the grid still looks plausible at a glance. Audit the printed gate map itself before you audit any solution: walk every dotted run from one end to the other, confirm it is continuous, confirm it ends at a black cell or the frame at both ends, and count the gates. That count is not bookkeeping. It must equal the number printed in the open circle, exactly, because the circle's number is a promise the buyer will count against.
The order rule is the part solvers actually solve with, and the part keys most often get wrong. A gate's number lives in the black cells at its ends; a correctly printed gate carries either no number, or the same number at both ends — and that sameness is itself an audit line, because a gate numbered 2 at one end and 3 at the other is two different instructions printed on one gate, and no loop can obey both. Where a black cell touches several gates, remember the tie-break: the cell's number speaks only for the gate that repeats that number at its other end. State that on the rules page, and audit it explicitly, because it is the one rule a buyer cannot guess from the picture alone.
Uniqueness is the part of the contract a plausible loop cannot promise. A course can usually be threaded in more than one order-respecting way if the setter only checks that a loop exists — gates left unnumbered are free, and free gates are where second solutions hide — and a puzzle whose course can be run two ways tells one of its two correct solvers they are wrong. The fifth part therefore has to be proven, not assumed: an independent solve, or a solver run, that counts solutions and returns exactly one, with that one reachable by deduction rather than by trying a crossing both ways until one branch survives.
Verification: re-walk every loop, gate by gate, in order, then count the solutions
Verification is a separate pass from solving, done mechanically, ideally by a different method than the one that made the puzzle. Solve each puzzle once as a buyer would, by deduction only, and keep the solve honest: if you guessed, and the guess worked, that puzzle has not been shown to have one solution, and it goes back. Then run the structural audit on the key, in this order. One: gate-map audit — every dotted run continuous, ending at black or frame at both ends, counted as one gate however many cells it spans. Two: total audit — the gate count equals the number printed in the open circle, on the puzzle page and the key page alike. Three: loop audit — the key is one single loop through cell centres, orthogonal only, with no crossing, branch, or revisited cell, starting and ending at the circle cell. Four: crossing audit — the loop passes every gate exactly once, perpendicularly, and no gate is run along or skipped. Five: order audit — walking the key from the start circle in one direction, the numbered gates are met in exactly their numbered order, 1 first, with unnumbered gates falling anywhere; then walk it in the other direction and confirm the reversed order also reads correctly, since the buyer may run the course either way. Six: ends audit — every numbered gate carries the same number at both ends, and every multi-gate black cell's number is assigned by the both-ends rule. Seven: uniqueness audit — a second, independent solve, or a solver run, that counts solutions and returns exactly one. Eight: consistency — puzzle page, key page and any thumbnail or marketing sample of that puzzle are the same puzzle, with the same black cells, the same gates and the same numbers in the same places.
Keep the audit results with the book's files, puzzle by puzzle. When a corrected edition ships, that record is how you know which puzzles actually changed and which were only suspected. It is also how you answer the buyer who found a real error: not with an apology and a shrug, but with the corrected puzzle, the audit lines that now pass, and the corrected file sent to everyone who bought the book — which is where the delivery side of this business, covered below, stops being administration and becomes the difference between a one-star review and a loyal repeat buyer.
Difficulty is gate order pressure and course shape, not just grid size
Grid size is the weakest difficulty lever in suraromu, and the one covers lean on hardest. Size does lengthen the course, but a large grid whose gates are nearly all numbered hands the solver the whole route as a join-the-dots exercise, while a small grid with few numbers, long gates and a loop that must double back past its own earlier legs can stop an experienced solver cold. The real levers are these. Numbered share: how much of the course the numbers fix — every numbered gate is a confirmed waypoint, and a book can be graded by how far apart those waypoints sit. Gate length: a long gate spans more of the grid, constrains more cells at once, and is more likely to force the loop's hand several cells away. Order spacing: gates numbered consecutively but placed far apart force long, deducible runs between certainties, while clustered numbers settle a corner and leave the rest free. Course shape: a loop that stays in open country is found by following local pressure; a loop threaded through narrow passages between black cells, touching its own earlier path on both sides, is where deductions stall and restart.
Grade a book by testing solves, not by measuring grids. Time honest solves across the set, note where each puzzle's deductions stall and restart, and order the book so difficulty genuinely climbs — early puzzles with most gates numbered and short runs between them, later puzzles with sparse numbers, long gates and tight passages. Print the grading honestly: "easy" should mean the numbers guide you most of the way round, not merely that the grid is small. A buyer who trusts your grading buys the next volume; a buyer who was ambushed by an unnumbered back half on page three of the easy book leaves a review about that instead.
Print honesty: the page is the interface
A suraromu page is read in pencil first and pen last, and the print has to survive both — starting with its gates, because the dotted line is this genre's most fragile mark. A gate that prints too faint reads as ordinary grid; a gate that prints too heavy reads as a wall the loop may not cross at all, and both misreadings make a correct puzzle unsolvable as printed. Print gates at a weight and dash a buyer cannot confuse with either the grid lines or the black cells, and check them at final size, not on a zoomed screen. The black cells carry the second legibility load: their numbers must stay readable white-on-black at book size, because a 3 misread as an 8 is not a harder puzzle, it is a different one, and the open start circle must be unmistakable — ringed, numbered, and different from every other mark on the page — since the whole order audit hangs off finding it. Your key must print the finished loop boldly, with the gates still visible underneath it, so a buyer can re-walk your loop crossing by crossing against their own attempt instead of taking the picture on faith.
Proof the final PDF, not the working file. Export at the exact trim size, print one puzzle and its key on a home printer at 100 percent, and solve the printed puzzle with the printed rules page as your only reference. Check the three things screens hide: whether every gate is visible as a gate after the page has been photocopied once — classrooms and care settings will photocopy it — whether the black-cell numbers and the start circle's number still read at arm's length, and whether a pencil loop in progress is distinguishable from the dotted gates it crosses, because the moment a buyer draws a leg they start comparing their page to yours. If a puzzle needs a screen's zoom to tell a gate from a grid line, it is not ready to be a download.
Licensing, provenance, and the download itself
State the licence where the buyer decides, not buried after purchase: who may solve the puzzles (one person, a household, a classroom, a club, a care setting), how many copies they may print, whether a teacher may hand a page to thirty students, whether a club may run one puzzle as a group activity, and whether the file itself may be shared, resold or republished — and say plainly that sharing the file is not the same as sharing a printed page. Puzzle books are bought heavily by teachers, club organisers and carers, and those buyers are trying to comply; a licence they cannot find reads to them as a licence that says no. Say how the book was made, too: hand-set, software-generated and hand-checked, or software-generated and mechanically audited. Provenance is not an apology — in this genre it is a quality claim, as long as it is specific. "Generated, then every loop re-walked from the start circle, gate by gate, in order, and every puzzle proven to have exactly one solution" is a claim a buyer can weigh; "high quality puzzles" is not.
Delivery is the last part of the contract. The buyer should get the file immediately, from a link that works the first time, on the device they bought it on, with re-downloads available when — not if — they lose it. Send a corrected edition to every past buyer when one ships; do not wait for them to discover the errata the hard way. I run my own download delivery through FileFreight — flat monthly pricing instead of a cut of every sale, expiring links, and updated files reaching past buyers without me re-emailing attachments by hand — but whatever you use, test it as a buyer: pay, receive, download, lose the file, recover it, and receive an update, before you ask strangers to trust it with money.
The launch checklist
- Every puzzle solved by deduction alone — no guessed step in any solve, start to finish.
- Gate-map audit passed: every dotted run continuous and counted once, ending at black or frame at both ends.
- Total audit passed: the gate count equals the number in the open circle, on puzzle pages and key pages alike.
- Crossing and order audit passed: the key crosses every gate exactly once, and the numbered gates in exactly their numbered order, walked in both directions.
- Uniqueness audit passed: exactly one loop satisfies the loop, gate and order rules, and it is the loop printed in the key.
- Print proof passed: gates, black-cell numbers and the start circle legible on a home-printed page at final size, after one photocopy.
- The errata rule honoured in advance: any gate crossed twice or not at all in the key, any numbered gate out of order, any gate count disagreeing with the circle, any mismatched gate-end numbers, any second solution or any forced guess means a corrected file goes to every buyer, not just the one who noticed.
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